Method and system for adjusting the amount of energy delivered to a handpiece of a surgical system based on feedback. A table is generated that correlates differences between voltages and rates of change of a voltage of the output of a charging element of the surgical system. Charge values of the table, such as minimum and maximum charge rates, can be generated using profile pulses and the time that is required for a pulse to reach a predetermined voltage. Intermediate charge rates can be determined using interpolation or other suitable methods. The output of the charging element is monitored at a voltage source, such as a capacitor, to determine first and second voltages at different times. These voltages are reduced if necessary for compatibility with electronic components and converted into digital values. A difference between two digital values is determined, and the determined difference is used to determine a corresponding rate at which the charging element charges the voltage source. The charge rate is provided as an input to the charging element to dynamically adjust the charge rate which, in turn, dynamically adjusts the energy provided by the voltage source to the liquefaction handpiece.